Water-soluble carboxyethyl starch ethers



Patented Apr. 6, 1943 UNITED STATES PATENT OFFICE 2,316,128 WATER-SOLUBLE CARBOXYETHYL STARCH ETHERS Louis H. Bock, Huntingrlon Valley, and Alva L. Houk, Philadelphia, Pa., assignors to Riihm &

Haas Company, Philadelphia, Pa., a corporation 01 Delaware No Drawing. Application February 21, 1942, Serial No. 431,840

4 Claims. (Cl. 260-209) 1 This-invention relates to fi-carboxyethyl ethers of starch which are soluble in water and which result by the reaction of alkali, starch, and acrylonitrile.

The soluble carboxyethyl ethers of starch are prepared by suspending starch in a dilute solution of a strongly alkaline hydroxide and reacting the starch with acrylonitrile. The starch may be of root origin, such as tapioca, or from a grain,

To a suspension of 33 parts of tapiocastarch in 300 parts of water were added 20 parts of a 20% sodium hydroxide and 2.6 parts of acrylonitrile. The resulting viscous solution was mixed of medium viscosity.

Example 2 To 33 parts of potato starch in 300 parts of such as wheat or corn, and may be in a raw state at Were added 20 parts of 20% sodium hyor in a elatinized or solubilized state which has dioxide d -6 parts of acrylonltrile. After the been reached without appreciable degradation. mixture s stirred for S x hours at 50 0., itwas As the hydroxide there may be used an alkali allowed to stand overnight before e n e metal hydroxide, such as lithium, sodium, or poized With hydrochloric acid. A thin solution of tassium hydroxide, or a strongly basic quaternary y slight turbidity w s f edammonium hydroxide, such as tetramethyl am- Example 3 monium hydroxide, trimethyl benzyl ammonium hydroxide'dimethyl dibenzyl ammonium hydrox TO 330 parts Of wheat starch were added 100 ide, etc., or mixtures of strongly basic hydroxides. Parts or 10% Sodium hydroxide and then in The concentration of the alkali may be varied small Portions 106 Parts acryioniiiriiefrom about 1% to about 10% and the proportion in! was continued for five hours at room of alkali may be conveniently variedfrom 0.025 peratirei after which 1,000 Parts of Water was t b t 2 mols per glucose unit f the Starch. added. The reaction mixture was left standing The proportions of acrylonitrile used in preparthree days and then neutralized With ing the water-soluble carboxyethyl ethers of acetic acid to form a slightly turbid solution of starch may be varied from about 0.1 to about 1.5 10w vismsityl mols per glucose unit. The upper limit is not The water-soluble products of s invention sharp, since starch itself can be rendered soluble are useful as sizing agents for yams, fabrics, P by other means, but, as the proportion is inand the like- They are aliso Useful is P creased above one moi of acryionitrile per glucose tiVQCOiIOidS' which stabilize dispersions or e u t, t becomes increasingly necessary to slons, and which are useful as spreading and dcmote the reactions involved by altering time and with! agents in insecticidal and fungicidal temperature. p ys- The temperatures at which the reaction may we claim: r b performed are not critical except that it is 1. The process of preparing a water-soluble not desirable to maintain the starch reaction carbflyethyi ether o starch which comprises emixture at such high temperatures as to cause acting by mixing within the temperature 91.186 of degradation. For practical purposes, the temand about s aroh, a 1% to 10% solution pefature of the mixture of starch, alkali, and of a strongly basic, water-soluble. hydroxide, and acrylonitrile should be maintained between 0 C. 40 acrylonitrile, the proportion of hyd o e bein and about 0 At the higher temperatures 0.025 to about 2 mols and of acrylonitrile being Shorter times are generally r q to render about 0.1 to about 1.5 mols per glucose unit of the the product water-soluble. Shorter times are Starchlikewise favored by lower proportions of acrylo- The Process of Preparing a Wat r-Soluble nitrile. With 0.1 to 0.5 mol of acrylonitrile, for csrboxyethyl ether of starch which p ises reexample, the reaction requires only five or six acting by mixing between and 0 C. starch, a hours for conversion to awater-soluble form. As 1% m 10% solution of sodium y o de, and more acryionitrile is used, in general more time acrylonitriie, the Proportion of hydroxide being must be allowed for rendering the products water- 0-025 to 2 mols and of acryionitliie being about so1ub1e 0.1 to about 1.5 mols per glucose unit of the Further details of the preparation of t starch. t soluble carboxyethyl ethers of starch are given in The process ofciaim 2 in Wilioh the s a c the following examples: is tspiOcs starch- 4. A water-soluble p-carboxyethyl ether of Example 1 starch.

LOUIS H. BOCK. ALVA L. HOUK.- 

